4-(2-aminoethyl)phenol

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Data is from peer reviewed journal

Justification for type of information:

Data is from peer reviewed journal

Qualifier:

according to guideline

Guideline:

other: as mentioned below

Principles of method if other than guideline:

Adsorption study was conducted for determining the adsorption capacity of test chemical 4-(2-Aminoethyl)phenol on the surface of albumin-modified silica.

GLP compliance:

not specified

Type of method:

other: No data available

Media:

soil

Specific details on test material used for the study:

- Name of test material : 4-(2-aminoethyl) phenol
- Common name : Tyramine
- Molecular formula : C8H11NO
- Molecular weight : 137.1809 g/mol
- Smiles notation : NCCc1ccc(O)cc1
- InChl : 1S/C8H11NO/c9-6-5-7-1-3-8(10)4-2-7/h1-4,10H,5-6,9H2
- Substance type: Organic
- Physical state: Solid

Radiolabelling:

not specified

Test temperature:

20 ± 2⁰C

Analytical monitoring:

not specified

Details on sampling:

- Concentrations: Test chemical conc. used for the study was 1 mmol/l, respectively.

Details on test conditions:

TEST CONDITIONS
- pH: pH value ranges from 2-8, respectively

TEST SYSTEM
- Amount of soil/sediment/sludge and water per treatment (if simulation test): 0.1 g of Protein containing silica was used for the study.
- Measuring equipment: After centrifugation (8000 rpm, 20 min) of test samples, silica was separated and amine concentrations were determined on a Specord M-40 spectrophotometer.

Computational methods:

- Other: The adsorption constant value was calculated using the Langmuir equation.

Key result

Temp.:

20 °C

Remarks on result:

other: %adsorption of test chemical 4-(2-Aminoethyl)phenol on finely dispersed silica and albumin-modified finely dispersed silica at pH 7.0 was determined to be approx. 5 and 25%, respectively.

Transformation products:

not specified

The character of amine adsorption on protein-modified silica differs significantly from the adsorption on the initial sorbent; on a surface of finely dispersed silica, the adsorption begins only at pH > 5 and increases with pH. For protein-containing silica, the pH dependences of adsorption pass through a minimum that coincides with the isoelectric point of BSA.

 

The constants calculated by the Langmuir equation and the maximum adsorption values are given in the table. The constants of amine adsorption on the initial silica are lower by nearly an order of magnitude than the constants of amine adsorption on the surface of protein-containing silica. The maximum adsorption of tyramine is almost the same for both adsorbents.

 

Table:Parameter of biogenic amine adsorption on surface of initial (FDS) and albumin-modified finely dispersed silica.

 

 

Amine	Protonation constant, logKa	FDS		FDS + BSA
		logK	Amax, mmol/g	logK	Amax, mmol/g
Tyramine	9.5	1.43	0.20	2.56	0.23

Validity criteria fulfilled:

not specified

Conclusions:

The maximum adsorption value of test chemical 4-(2-Aminoethyl)phenol on finely dispersed silica and albumin-modified finely dispersed silica was determined to be 0.20 & 0.23 mmol/g, respectively and percentage adsorption of chemical 4-(2-Aminoethyl)phenol at pH 7.0 and a temperature of 20 ± 2⁰C was determined to be approx. 5 and 25%, respectively.

Executive summary:

Adsorption study was conducted for determining the adsorption capacity of test chemical 4-(2-Aminoethyl)phenol (CAS no. 51-67-2) on the surface of albumin-modified silica. Albumin-modified finely dispersed silica samples were prepared via protein adsorption from an aqueous solution. BSA (6 g) was dissolved in water (500 ml), finely dispersed silica (10 g) was added, the system was stirred, and pH was brought to 5. In 1 h, the obtained suspension was centrifuged and silica was separated, washed three times with water, filtered off, and dried at room temperature.In the residual equilibrium solution and the filtrates, the concentration of albumin was determined based on an UV absorption band (λ= 268 nm) using the calibration plot constructed preliminarily. In this way, a silica sample was obtained with an albumin content of 430 mg/g sorbent (300 mg protein per 1 g sample). Tyramine adsorption was studied at room temperature (20±2°С). Amine solutions (10 ml, 1 mmol/l) were added to weighed portions of protein-containing silica (0.1 g) and the pH values of the systems were brought to desired values in the range of 2–8. The samples were stirred for 1 h (as was shown previously, this time is sufficient for the adsorption equilibrium to be established), with the pH values being repeatedly controlled using an EV-74 pH meter. After centrifugation (8000 rpm, 20 min), silica was separated and amine concentrations were determined on a Specord M-40 spectrophotometer. The UV absorption spectra of both amines were preliminarily studied depending on the concentration and pH of their solutions. It was found that, for tyramine, the positions and intensities of absorption bands are independent of pH; for tyramine,λmax= 275 nm,ε= 1560 (l mol–1 cm–1). The absorption bands of the amines almost coincide with the absorption spectrum of BSA; therefore, the equilibrium concentrations of the amines were determined from their absorption band intensities, which were estimated by subtracting the absorption corresponding to the concentration of the protein desorbed into a solution at a given pH. The adsorption values of amines were determined from the difference between the initial and equilibrium concentrations and expressed in percents.The adsorption values calculated from the difference between the initial and equilibrium concentrations were expressed in mmol/g.The adsorption constant value was calculated using the Langmuir equation. The maximum adsorption value of test chemical 4-(2-Aminoethyl)phenolon finely dispersed silica and albumin-modified finely dispersed silica was determined to be 0.20 & 0.23 mmol/g, respectively and percentage adsorption of chemical 4-(2-Aminoethyl)phenolat pH 7.0 and a temperature of 20 ± 2⁰C was determined to be approx. 5 and 25%, respectively. Thus based on the %adsorption, it indicates that the substance 4-(2-Aminoethyl)phenol has a negligible to low sorption tosoil and sediment and therefore have rapid to moderate migration potential to ground water.

Description of key information

Adsorption study was conducted for determining the adsorption capacity of test chemical 4-(2-Aminoethyl)phenol (CAS no. 51-67-2) on the surface of albumin-modified silica

(N. N. Vlasova, et. al; 2011). Albumin-modified finely dispersed silica samples were prepared via protein adsorption from an aqueous solution. BSA (6 g) was dissolved in water (500 ml), finely dispersed silica (10 g) was added, the system was stirred, and pH was brought to 5. In 1 h, the obtained suspension was centrifuged and silica was separated, washed three times with water, filtered off, and dried at room temperature.In the residual equilibrium solution and the filtrates, the concentration of albumin was determined based on an UV absorption band (λ= 268 nm) using the calibration plot constructed preliminarily. In this way, a silica sample was obtained with an albumin content of 430 mg/g sorbent (300 mg protein per 1 g sample). Tyramine adsorption was studied at room temperature (20±2°С). Amine solutions (10 ml, 1 mmol/l) were added to weighed portions of protein-containing silica (0.1 g) and the pH values of the systems were brought to desired values in the range of 2–8. The samples were stirred for 1 h (as was shown previously, this time is sufficient for the adsorption equilibrium to be established), with the pH values being repeatedly controlled using an EV-74 pH meter. After centrifugation (8000 rpm, 20 min), silica was separated and amine concentrations were determined on a Specord M-40 spectrophotometer. The UV absorption spectra of both amines were preliminarily studied depending on the concentration and pH of their solutions. It was found that, for tyramine, the positions and intensities of absorption bands are independent of pH; for tyramine,λmax= 275 nm,ε= 1560 (l mol–1 cm–1). The absorption bands of the amines almost coincide with the absorption spectrum of BSA; therefore, the equilibrium concentrations of the amines were determined from their absorption band intensities, which were estimated by subtracting the absorption corresponding to the concentration of the protein desorbed into a solution at a given pH. The adsorption values of amines were determined from the difference between the initial and equilibrium concentrations and expressed in percents.The adsorption values calculated from the difference between the initial and equilibrium concentrations were expressed in mmol/g.The adsorption constant value was calculated using the Langmuir equation. The maximum adsorption value of test chemical 4-(2-Aminoethyl)phenolon finely dispersed silica and albumin-modified finely dispersed silica was determined to be 0.20 & 0.23 mmol/g, respectively and percentage adsorption of chemical 4-(2-Aminoethyl)phenolat pH 7.0 and a temperature of 20 ± 2⁰C was determined to be approx. 5 and 25%, respectively. Thus based on the %adsorption, it indicates that the substance 4-(2-Aminoethyl)phenol has a negligible to low sorption tosoil and sediment and therefore have rapid to moderate migration potential to ground water.

Additional information

Various experimental key and supporting study for the target compound 4-(2-Aminoethyl)phenol (CAS No. 51-67-2) and supporting study for its structurally similar read across substance were reviewed for the adsorption end point which are summarized as below:

 

In an experimental key study from peer reviewed journal (N. N. Vlasova, et. al; 2011),adsorption experiment was conducted for determining the adsorption capacity of test chemical 4-(2-Aminoethyl)phenol (CAS no. 51-67-2) on the surface of albumin-modified silica. Albumin-modified finely dispersed silica samples were prepared via protein adsorption from an aqueous solution. BSA (6 g) was dissolved in water (500 ml), finely dispersed silica (10 g) was added, the system was stirred, and pH was brought to 5. In 1 h, the obtained suspension was centrifuged and silica was separated, washed three times with water, filtered off, and dried at room temperature.In the residual equilibrium solution and the filtrates, the concentration of albumin was determined based on an UV absorption band (λ= 268 nm) using the calibration plot constructed preliminarily. In this way, a silica sample was obtained with an albumin content of 430 mg/g sorbent (300 mg protein per 1 g sample). Tyramine adsorption was studied at room temperature (20±2°С). Amine solutions (10 ml, 1 mmol/l) were added to weighed portions of protein-containing silica (0.1 g) and the pH values of the systems were brought to desired values in the range of 2–8. The samples were stirred for 1 h (as was shown previously, this time is sufficient for the adsorption equilibrium to be established), with the pH values being repeatedly controlled using an EV-74 pH meter. After centrifugation (8000 rpm, 20 min), silica was separated and amine concentrations were determined on a Specord M-40 spectrophotometer. The UV absorption spectra of both amines were preliminarily studied depending on the concentration and pH of their solutions. It was found that, for tyramine, the positions and intensities of absorption bands are independent of pH; for tyramine,λmax= 275 nm,ε= 1560 (l mol–1 cm–1). The absorption bands of the amines almost coincide with the absorption spectrum of BSA; therefore, the equilibrium concentrations of the amines were determined from their absorption band intensities, which were estimated by subtracting the absorption corresponding to the concentration of the protein desorbed into a solution at a given pH. The adsorption values of amines were determined from the difference between the initial and equilibrium concentrations and expressed in percents.The adsorption values calculated from the difference between the initial and equilibrium concentrations were expressed in mmol/g.The adsorption constant value was calculated using the Langmuir equation. The maximum adsorption value of test chemical 4-(2-Aminoethyl)phenolon finely dispersed silica and albumin-modified finely dispersed silica was determined to be 0.20 & 0.23 mmol/g, respectively and percentage adsorption of chemical 4-(2-Aminoethyl)phenolat pH 7.0 and a temperature of 20 ± 2⁰C was determined to be approx. 5 and 25%, respectively. Thus based on the %adsorption, it indicates that the substance 4-(2-Aminoethyl)phenol has a negligible to low sorption to soil and sediment and therefore have rapid to moderate migration potential to ground water.

 

Another adsorption study was conducted for determining the adsorption capacity of test chemical4-(2-Aminoethyl)phenol (CAS no. 51-67-2) on the surface of highly dispersed silica. The adsorption of biogenic amines was studied at room temperature (20±2°C). Mix equal volumes of initial silica suspension (20 g/l) prepared in the presence of 0.002 or 0.02 M sodium chloride, and 1 mM amine solutions so that concentrations of silica and amines in prepared suspensions were 10 g/l and 0.5 mM, respectively, and their ionic strength was 0.001 or 0.01. Then, suspension samples (10 ml) were taken, their pH was adjusted to the required pH values within the pH 4–8 range by adding alkali or acid solutions, and were stirred for 1 h. It was established preliminarily that this time is sufficient to attain an equilibrium adsorption. The values of suspension pH were checked periodically (with an EV-74 ionomer). After centrifugation (8000 rpm, 20 min), silica was separated and amine concentration was determined on a Specord M-40 spectrophotometer (Germany). The values of adsorption were calculated by the difference between final and equilibrium concentrations. Preliminarily, we measured absorption spectra of amines in the UV region as a function of the concentration and pH of their aqueous solutions. It was found that, for tyramine, the positions of absorption bands and intensities are almost identical of pH; for tyramine, λmax= 275 nm,ε= 1560 (l mol–1 cm–1).The percentage adsorption of chemical 4-(2-Aminoethyl)phenol on highly dispersed silica at pH 7.0 and a temperature of 20 ± 2⁰C was determined to be approx. 8%, respectively. Thus based on the %adsorption, it indicates that the substance 4-(2-Aminoethyl)phenol has a low sorption to soil and sediment and therefore have rapid migration potential to ground water.

 

 

In a supporting weight of evidence study from authoritative database (HSDB, 2017) for the read across chemical p-cresol (CAS no. 106-44-5),adsorption experiment was conducted in a brookston clay loam soil for determining the adsorption coefficient (Koc) value of read across chemical p-cresol (CAS no. 106-44-5) using the Batch Equilibrium Method. The study was performed according to OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method). The adsorption coefficient (Koc) value of test substance p-cresol was determined to be 49 (Log Koc = 1.69). This Koc value indicates that the substance p-cresol has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

 

On the basis of above overall results for target chemical 4-(2-Aminoethyl)phenol (from peer reviewed journals) and for its read across substance (from authoritative database HSDB), it can be concluded that the test substance 4-(2-Aminoethyl)phenol has a negligible to low sorption to soil and sediment and therefore have rapid to moderate migration potential to ground water.